her voice is the sound of waves (waves against the cliffs)
by Skatzaa
Summary: The men throw her overboard just before the storm hits. Katara wakes on the ocean floor, painfully and inexplicably alive. (The vengeful mermaid au that no one but me asked for. Cross posted on ao3.)


**Inspired by a post on tumblr.**

 **I won't be doing ZK Week this year, bc of when school starts for me, and the fact that I still have to finish my big bang fic for another fandom. Also, I'm working on something rather big for this fandom that probably won't be ready for like, six years.**

 **In lieu of all that, you can have this, which trustworthy sources have informed me is "actually pretty cool" (thanks Bree). This isn't set in canon, so imagine it's some undefined time period in some undefined world. I know, super specific.**

 **Enjoy!**

* * *

The men throw her overboard just before the storm hits.

Katara struggles, twisting in their grasp. She manages to kick one in the face before they push her skirts and lash the ropes around her thighs, knees, ankles. The knots are tight; the rope cuts into her skin when she thrashes.

The sky is dark and bruised. The ocean, when she glimpses it from the corner of her eye, is a gaping eternity ready to swallow her whole.

A man—Bato. Katara can't believe her father's friend would do this, but there is wild fear in his eyes. Men are foolish when they are afraid.

Bato binds her hands.

Katara twists in their arms, sees the mast and the deck and countless boots. Her brother is nowhere in sight. Katara screams for him, but he doesn't answer. She doesn't want to know why.

She tastes salt on her tongue and isn't sure if it's from her tears or the ocean.

The men heave her overboard as the rain starts. Droplets land on her cheeks, one, two, and then she is in the water.

Katara cannot swim, tied as she is. She holds her breath as she sinks. The salt stings her eyes, but she keeps them open. She sees the tail of the ship's figurehead, and then only the darkness of the ocean.

Her lungs ache. The cold of the deep presses in close, bites at her skin. Katara can hear nothing but her own heartbeat, struggling against the vastness that holds her.

Something brushed her foot, races along her leg, tangles in her hair.

Katara screams.

The last of her air rushes out. The harsh, burning ocean water fills her mouth and throat. Katara chokes and gags, but the water doesn't subside.

Katara breathes in and in, tasting nothing but salt. She is choking, drowning. She is dying.

And then she breathes out.

* * *

Her father sends them away when Katara is sixteen and Sokka seventeen. He says the island isn't safe anymore, especially for the children of the chief. He says Bato will protect them, take them somewhere safer. He doesn't say where.

Katara wishes she had fought harder to stay.

* * *

The ocean speaks to her, sometimes, in its deep, booming voice.

It teaches her its secrets, shows her all the hidden caves and vents. The vents sear her skin, but Katara withstands it. Anything is better than the piercing, crushing cold she cannot shake.

She doesn't know if the ocean speaks to the others. She doesn't ask.

* * *

Katara wakes on the ocean floor, painfully and inexplicably alive.

Her hands are still tied, so she brings them to her face and gnaws at the rope. It falls away faster than she expects. Her teeth clack uncomfortably, as if they are suddenly too big for her mouth.

Her body feels different, heavier and lighter at the same time. Katara cannot see through the darkness of the deep.

She reaches for the ropes on her legs, brushing her skirts aside. Her fingers touch rope, and then scales.

Katara stills.

Hands trembling, she tries to grab her feet.

All she finds is a slippery fin.

Katara screams, but it's lost in the vast expanse of the sea. The salt water burns her throat going down.

She tears off her dress and her wrappings, exploring, trying to discover what else about her body has changed, has forced her to stay alive.

The scales extend from her belly button to where the fin begins. Her hips are shoulders are slimmer, the dip where her waist once was has filled in. Her breasts are nearly flat. Her teeth, when she remembers the ease with which she bit through the bonds on her wrists, are now pointed and sharp.

Katara sucks in breath after breath of ocean water and each one burns.

She gathers her tail—a _tail_ —under her and shoves off the seabed. She can't see here, but maybe if she swims enough, she'll understand what's happened to her. Maybe she can—maybe—

Katara swims and swims.

She cannot adjust to the tail. She is used to long bones and a few joints, legs that fold only in certain ways and places. Not so, with the tail. It flips and bends easily, twisting in places where she isn't expecting movement. It's disconcerting, and Katara has to force herself to ignore it.

She swims for what feels like an eon. If she cries at all, she doesn't know, because the ocean doesn't discriminate between the tears of drowned girls and its own waters.

She's begun to shiver—from the cold of the shock or maybe both—when she realizes she can see the strands of her hair floating around her face. Katara looks up.

There's light.

She swims faster. The ocean tugs at her, but she ignores it.

Katara breaks the surface, gasps for breath. The air tears through her. She coughs, gags on the taste of it.

Then the wave crashes down on her.

The force of it sweeps her under again, and the next swell grabs her before she can get her bearings. Katara tumbles through the storm—it must be a storm, maybe the same one the sailors sacrificed her to.

She hopes the gale takes them all.

Something latches onto her hand and drags her down.

Katara thrashes, tries to use the extra length of her tail to her advantage. It doesn't work.

Then she hears a voice, a woman's voice, harsh and crackling, say, "Stupid girl, do you want to get us killed?"

Katara stops struggling.

Her savior pulls them down until they are out of the storm's grasping reach, then releases Katara's wrist.

She looks around herself and sees a girl of no more than twelve sneering at her.

The girl has a tail; it's red and orange and black, like a dying coal.

Katara remembers, and glances down at her own tail. It's an ugly, bruised purple-blue, like the storm clouds above. The ropes the men tied her with dig beneath her scales. She scrabbles for the knots but they're too embedded. All she does is stir up the blood oozing from the cuts.

She sees that the girl is frowning at the ropes when she looks up again.

"They got you good," the girl says. "Usually the ropes slip off during the change."

Usually. Katara wonders how many of them there are down here, choking on salt and air alike.

The girl smiles. Her teeth are viciously sharp. "My name is Azula."

"I'm Katara."

Azula studies her for a moment, head tilted to one side.

"Interesting. We don't have many islanders here." Then she turns with a quick flick of her tail and says, "Come on. Hama wants to meet with you, and she never leaves the depths."

Katara follows Azula cautiously, wondering how such a young girl could have a woman's voice.

"A piece of advice," Azula says, her voice trailing out behind her. "Unless you're hunting, stay away from the surface. You'll never get your deep-sight otherwise."

* * *

The ocean teaches her how to sing like the waves, to lure in fish and men alike, to sound mysterious and alluring.

It shows her how to whisper to the water, to twist it to her needs and bend it to her whims.

It teaches her to hunt.

* * *

Hama's hair and scales have faded to white. Katara has no idea what their original colors were.

Her eyes are huge and pitch black. Katara recoils.

Hama laughs, and it sounds like ice cracking beneath unsteady feet. Then she turns and swims down. Azula follows, her hand once more clasped tightly on Katara's wrist, pulling her along.

When they stop, Katara can't see, but she can hear whispers.

"Tell me, child," Hama says. "Have you been wrongfully killed?"

Katara nods, and then feels foolish, because she can't believe anyone can see down here. Hama continues regardless.

"Were they men, afraid of your powers?"

Katara doesn't think it's her power they feared, but maybe there's a power to be found in one's gender, if it can make men abandon their promises so easily. She nods again. The whispers grow louder.

"Would you like revenge?"

Katara stares down into the blackness and calls to mind the sight of her tail, new and unasked for, sliced open and bleeding. She breathes. The water burns.

She nods, and the whispers erupt.

* * *

The first time she goes hunting, Katara still doesn't have her deep-sight. Sometimes she can see silhouettes drifting through the darkness, but that's all. The light of the moon stings her eyes as she nears the surface, but it cannot compare to every breathe she takes. She waits, still and silent in the water, listening for ripples like the ocean taught her.

An echo comes from the north, where she likes to imagine Bato and his crew drowned.

Another echo.

Katara follows the sound, skimming the edge of the waves. She's far closer to the surface than Hama or Azula would like her to be, but Katara doesn't care. The others are full of fear and hate in equal parts.

Katara doesn't feel anything, now.

She comes quickly to a small rowboat. The echoes come from the oars knocking against the hull.

Whoever this is, they aren't giving up, though they're miles from the shore.

Katara comes right up to the boat, sinking her tail beneath her. She presses her fingers into the wood and rises slowly. Her hair clings to her face and neck, so brittle from the salt already. It's started to break off when she brushes past things.

As always, Katara tries to breath the air. It tears at her lungs, vengeful and vicious, and she wonders if she isn't truly dead, living a half-life with only the ocean's will to keep her moving.

She takes another breath, because the pain is almost addicting, and begins to sing.

Her voice is the sound of waves crashing against the shore, the rush of water from the deepest vents, the whales mourning the loss of one of their own. She pushes off from the boat with her fingertips alone and floats into open water.

The man is already leaning toward her, hanging over the water, and Katara draws closer, reaches out her arm. All she needs is a little more and she'll—

The moonlight illuminates his face.

It's _Sokka_.

Katara jerks back. She stops singing, and the silence is loud in her ears. The only thing louder is her heart, thundering in her chest.

There's a cut on his temple and his eyes are bruised and almost swollen shut.

Katara sucks in a breath and centers herself on the pain.

She turns and disappears back into the ocean without a sound. She wants to race away, wants to hide herself in the deepest cave she can find for the rest of however long the ocean decides to bind her to itself.

But then she hears Sokka ask, so softly she can barely hear it over the sound of her heartbeat, " _Katara?"_ and his voice is scratchy and broken.

Katara drifts to a stop and flips to face the surface.

Sokka asks again, and she reaches for the ocean. She whispers to it, asks for its help.

She can feel Sokka's tears hit the water as she forces the ocean to push him toward the shore.

* * *

Katara is sawing through the remainder of her hair with a sharpened rock when Azula rushes by, saying, "A ship, a metal ship!" over and over.

She hacks through the last lock and tries not to swing her head back and forth as she follows in Azula's wake. Her head feels light; strands of her hair sweep across the back of her neck now, no longer dragged down by their own weight.

Perhaps forty or so women, the most Katara has ever seen at one time, are gathered in the main cavern of the labyrinth they claimed as their own long before she joined their numbers. Excited murmurs swirl through the water as June whispers to Hama, jet black tail flicking impatiently.

She's heard of the metal ships, how they make voices echo in ways that can drag down a whole crew.

She's also heard Azula was on a metal ship when she was sent overboard, how her brother sat back and let it happen because he wouldn't go against their father.

Azula rips her fingers through her knotted hair as they wait for Hama to decide who will go, sharp teeth bared in a ferocious grimace.

Hama approaches them last. She gives Azula a nod and vicious smile, and then turns to Katara and says, "It's time for you to experience a real hunt."

Katara hears the unspoken words: it's time for you to start pulling your weight. She breathes and breathes and nods.

A dozen of them race from the caves. Laughter floats through the dark and it makes the back of her neck prickle.

Azula swims agitated circles around Katara, twisting around and around as they ascend. Katara reaches out a hand, brushes her fingers along the length of Azula's arm as she passes. It seems to calm her some, or at least enough that she's willing to stay by Katara's side.

It takes her longer than it should to notice how close to the surface they are, because there's something blocking out the moonlight.

It's a ship.

The ship is massive, many times the length of anything the islanders sail. Katara marvels at it and then lays a hand on Azula's shoulder when she starts tugging at her hair again. The ship doesn't echo like Sokka's rowboat did. Instead, it creaks and groans and the blades of its propeller roar through the water.

Hama whispers something, and it should be too quiet to hear over the ocean's booming voice in her ear, but Katara can _feel_ what she's meant to do. She flicks her tail and shoots away from Azula, taking up position near the port bow.

Hama whispers again, and they surge for the surface.

* * *

On her way back to where Azula is waiting for her, after she almost pulled her _brother_ down, Katara finds the sunken remains of a wooden ship.

The figurehead, a woman with a short tail and ample, uncovered breasts, smiles serenely up at her, unseeing and uncaring.

Katara feels the sea burn her throat. She would vomit, if there was anything in her stomach.

* * *

The day after the metal ship, Katara goes exploring.

She swims and swims, confused and curious. She's never gone this far without Azula by her side. She finds the entrance to what promises to be a labyrinth of caves and tunnels.

Moonlight still clings to her vision, so that she can't truly see where she's going. Instead, Katara takes random turns for a long time.

Then the water—already grasping and piercing—becomes even colder, and Katara knows she's made it to a larger cave.

"Who are you?" A voice asks.

Katara jerks back so hard her tail almost flips up over her head. The stranger laughs lightly, and though the woman's voice is as harsh and cracked as everyone else's, her laughter is bright and clear.

"I'm sorry," the woman says, and she brushes her hand against Katara's arm. "I didn't mean to startle you. My name is Ursa."

"I'm Katara," she says.

Ursa hums, and it sounds like waves on the shore.

"How did you get so far from the pod?"

Katara shrugs. "I decided to explore on my own. Azula is too cautious."

Ursa is quiet for a long time. Katara can feel the pulsing force of Ursa's tail moving through the water, barely a caress by the time it reaches her scales.

Finally, Ursa says, "You don't have to hunt. Hama's way isn't the only one."

She thinks of the boy she dragged down last night, the exhilarating power that rushed through her when she saw the fear on his face.

"Is that why you're out here all alone?"

Katara can barely make out Ursa's outline, but she can tell when she turns away.

"Yes."

* * *

They never manage to get the ropes off of her tail.

Eventually, her scales begin to grow around them and Katara learns not to wince when her tail bends in the wrong spots.

The cuts never stop oozing dark blood.

* * *

Katara thrusts her head and shoulders above a cresting wave and relishes in the burning, searing air.

Hama begins singing, and the rest throw their voices to bounce off the metal hull. Katara joins in.

Almost immediately, three men peer over the railing of the deck, trying to find her in the midnight sea.

She gives the ocean a little nudge and it sends tendrils creeping up the side of the ship. They wrap around the two on the outside edges and _yank_.

The men don't even fight.

Katara _pushes_ and rises on a wave. The man remaining doesn't look away from her as she draws closer. She realizes he's young, maybe Sokka's age, when she's level with him. He has a scar on his face. Katara sings like the tides and beckons with a finger.

The young man leans forward, close enough that she can feel his breath on her chin.

She sees the amber of his eyes right before she hooks her fingers in the grooves of his heavy armor and drops.

The sea cradles her but it drags her prey down, down. The cold seems to pierce the spell her voice wove and he begins to struggle, but it's too late. She folds the ocean around him and holds him beneath the surface.

His eyes are wide and wild and Katara gives him a terrible smile.

She doesn't wait for him to stop struggling before she turns to the ship and begins to sing once more.

* * *

Katara boards the ship wearing her second best dress, because Gran-Gran insisted that morning that the daughter of a chief must always represent her tribe. Sokka teases her about it. When Bato sees her from where he's waiting at the end of the gangplank for them, he mock-bows and says, "My lady."

Katara hits his shoulder but laughs anyway.

She kisses her father on the cheek and waves to Gran-Gran.

"See you soon!" She calls.

* * *

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 **Read On,**  
 **Skats**


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